Carbon TH E WOR LD OF T he level of carbon-dioxide (CO2) in the air in the northern hemisphere was 315 parts per million in 1958 and currently it is 390 (0.039 %) and continues to rise despite global efforts to reduce it; among others with carbon rights trading between countries and companies. The gas is held responsible for capturing sunlight and transforming it into heat. It serves as a greenhouse gas. Water vapour in the air has the same function and also methane (from cows and rice production) and nitrous oxide gases from bacterial soil live). Especially these gases contribute to the greenhouse effect as they are 300 times more effective than carbon dioxide. It is estimated that agriculture is responsible for about 11 percent of greenhouse gases caused by man. A reduction of greenhouse gas emission by agriculture could be a substantial means of mitigating its effect on climate change. An new tool to calculate the CO2 emitted in the production of crops or animals in agriculture is the Cool farm Tool (CFT) developed by dr. Jon Hillier with co-workers at the University of Aberdeen commissioned by Unilever. Recently with the aid of McCain potato agronomists at a few continents dr. Hillier and I made it potato specific: The CFT-Potato, soon to be aired at the www. The tool – an MS Excel spreadsheet – at page one requires the site and country the crop is in. This is important as some countries have a high emission level of electricity production where mainly coal is used (South Africa) whereas e.g. France has a low level as in this country the majority of electricity is from nuclear energy. When using power for water pumping or cooling the carbon load varies according to country. The farmer also has to declare the soil to be sandy, medium or heavy as heavier soils require more diesel to plough and to harvest. Soil organic matter, humidity and acidity are reported as they influence nitrogenous fertilizer break down to volatile compounds and high organic matter soils lose soil carbon when exposed to oxygen and is aggravated by working the land. Fertilizers – total amounts and type - such as ammonium POTATO R ESEARCH nitrate or urea are noted as well as the sources of potassium, phosphorus and calcium. Organic amendments also can be mentioned such as farm yard cow manure or pig slurry. The grower fills in the number of applications of herbicides, insecticides and fungicides. Based on these data the Tool sums up all the energy that is needed to produce the chemicals in the factory and how much CO2-equivalents of nitrous oxygen is emitted from the soil resulting from fertilization. Subsequently the grower completes a page with all operations such as plowing, ridging, destining, spraying, spreading, irrigation, on farm transport of materials and tubers and harvesting. The Tool then calculates – based on ASABE data of the American Society of Agricultural and Biological engineers - how much diesel and electricity is used and converts it into kg CO2. Finally the tool asks whether the product is washed, graded, loaded into a store and stored with ventilation and refrigeration and about the use (number and dose) of sprout suppressant. The original Tool did not contain information nor questions about irrigation, grading, storage and sprout control. So we collected data from various operations and came up with easy questions such as how many millimeter did you apply in total and for how many weeks did you store and how many degrees was the potato in the store cooler than the average outside temperature. From our data we know how much electricity it costs to irrigate one mm, or to cool potatoes down per degree for one week. We also changed some figures the ASABE data base clearly underestimated such as for subsoiling and harvesting. Finally the grower has to fill in the yield and the seed rate and the Tool calculates the CO2 emission associated with the production of one ton of potato, usually a few hundred kilograms. The tool is helpful in benchmarking different growing systems such as tropical highlands or temperate climates, dryland or irrigated farming, organic or current, low or high input production and stored or transported. Policymakers of governments and companies may use it to take decisions and develop strategies such as Walkers Crisps – see picture – to reduce the CO2 foot print. For individual growers at specific fields the tool as yet needs to be tested and possibly be fine tuned further. Anton Haverkort anton.haverkort@wur.nl 22 Potato World 2011 • number 1 Pagina 21
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